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Court rulings may result in groundwater discharges requiring NPDES permits

If the first two months of 2018 are any indication, events to play out over the rest of the year will have a major impact on what constitutes a “discharge” subject to regulation under Section 402 of the Clean Water Act (CWA). Three cases pending in different federal courts of appeals will address whether releases of pollutants to groundwater hydrologically connected to waters of the United States are subject to the National Pollution Discharge Elimination System (NPDES) permitting requirements of the CWA. In a fourth case, the Ninth Circuit recently weighed in on this issue by articulating a novel, broad rule for determining when a discharge occurs. Spurred on by these developments, and its own admittedly varied positions on this issue over the years, EPA is now seeking comment by May 21 on how to approach this issue.

How the courts and EPA resolve this question will dictate what releases potentially create liability under the CWA. For example, spilling or leaking materials conveyed by groundwater or subsurface flow to surface water may suddenly require NPDES permits. And under the Ninth Circuit’s recent decision, even pollutants washed into navigable waters by sheet flow may be regulated by the CWA. Unlike discrete point source activities traditionally required to obtain NPDES permits, these newly defined “discharges” would be difficult to anticipate—and seek permit coverage for—because these pathways to regulated waters may only be discernible after the fact. The four pending lawsuits represent attempts by citizen plaintiffs in each case to expand NPDES permit liability to unforeseen circumstances.

Nearly every industry has a stake in how EPA and the courts resolve this issue. If EPA and more federal judges follow the Ninth Circuit’s lead by broadly defining discharges regulated by the CWA, many companies and operations will see increased exposure to enforcement actions by citizen groups, EPA, and states authorized to implement the NPDES program. Submitting comments to EPA by May 21 and filing amicus briefs in pending litigation offer timely opportunities to inform how the Agency and judiciary will define the CWA’s reach.